The present invention relates to a grease trap and a method of decomposing edible oils and fats in the grease trap. In particular, the present invention relates to a method of decomposing edible oils and fats which are substantially contained in drainage from a restaurant kitchen by activating aerobic microorganisms, and a grease trap equipped with a decomposing unit for decomposing edible oils and fats.
It has been prohibited to discharge drainage from the kitchen of a restaurant into a sewer directly. As a conventional drainage treatment, the drainage from a restaurant kitchen is temporarily held in a grease trap, where oils and fats separate from water and float on the top surface of the drainage. In this grease trap, however, some oils and fats solidify on the drainage surface, some putrefy below the solidified layer and give out putrefying odours, and the others are deposited on a drainpipe to obstruct the flow of the drainage. In order to avoid these problems, the restaurant staff has to remove the oils and fats accumulated in the grease trap everyday or once in a few days. Regrettably, such oils/fats removal operation costs substantial money and labor.
Alternative methods of drainage treatment include an oils/fats dissolution method of dissolving the accumulated oils and fats into water and smoothly discharging the mixture of oils/fats and water, and an oils/fats decomposition method. These methods utilise naturally existing microorganisms and enzymes for their ability to decompose oils and fats or dissolve the same in water. However, the microorganisms are deactivated in such a disappointingly short period that they fail to give expected results and oils and fats clog the drainpipe in the end.
The microorganisms may be referred to as bacteria or germs in some occasions. In a scientific classification, however, it is difficult to identify the species of a microorganism. This is partly because the definition of "microorganism" includes a living organism in which various species of microorganisms coexist in huge population. In addition, enzymes are catalytic substances which gather and activate microorganisms. Accordingly, the term "microorganism" as used in the present specification also includes enzymes. Given the above interpretations, microorganisms can be classified into the following three categories:
(1) Aerobic Microorganisms which are active in the presence of air; PA1 (2) Anaerobic Microorganisms which are active in the rare presence of air, as observed in putrefying decomposition; PA1 (3) Facultative Microorganisms which turn aerobic or anaerobic to adapt to the environment, i.e. Aerobic/Anaerobic Microorganisms or Nonaerobic/Nonanaerobic Microorganisms.
Usually, anaerobic microorganisms are dominant in water, while aerobic microorganisms are dominant on the water surface which has contact with air. In the scope of the present invention, the drainage surface in the grease trap is covered with edible oils and fats substantially contained in the drainage. Therefore, it is theoretically reasonable and effective to activate aerobic microorganisms with the intention of promoting decomposition of oils and fats. In practice, however, oils and fats solidify on the surface of the drainage and float under water to form sludge. Under the circumstances, anaerobic microorganisms (putrefying bacteria) are activated to progress putrefaction, which continues for a long time and causes ammonia-like malodours. In order to improve air circulation and prevent the putrefaction, conventional drainage treatments practise aeration with the use of an underwater pump. The underwater pump forms air bubbles and releases them towards the water surface, where aerobic microorganisms are active in the abundant presence of air. Regrettably, most air bubbles fail to reach the water surface and aerobic microorganisms do not act, as expected, on the oils and fats floating on the surface. Under constant presence of surface oil/fat solids, insufficient air supply weakens the response of undersurface aerobic microorganisms and results in incomplete oils/fats decomposition. Moreover, undersurface aerobic microorganisms may either be extinguished or migrate into a sewer to get more air. In turn, anaerobic microorganisms grow dominant in the grease trap and eventually putrefy the oils and fats. Thus, mere application of an underwater pump is impractical for effective aeration.
As has been described, it is the most important problem in oils/fats decomposition for the drainage treatment to establish a manner of keeping or extending the life and oils/fats decomposition property of aerobic microorganisms.